<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        body {
            background: #000;
        }
        
        .mage {
            margin: 100px auto 0;
            width: 630px;
            height: 394px;
            padding: 10px 0 0 10px;
            background: #000;
            overflow: hidden;
            border: 1px solid #fff;
        }
        
        .mage ul {
            list-style: none;
        }
        
        .mage ul li {
            float: left;
            width: 200px;
            height: 187px;
            margin: 0 10px 10px 0;
            background-color: #fff;
        }
    </style>
</head>

<body>
    <div class="mage">
        <ul>
            <li>
                <a href="#"></a>
            </li>
            <li>
                <a href="#"></a>
            </li>
            <li>
                <a href="#"></a>
            </li>
            <li>
                <a href="#"></a>
            </li>
            <li>
                <a href="#"></a>
            </li>
            <li>
                <a href="#"></a>
            </li>
        </ul>
    </div>
</body>

</html>
<script src="jQuery版本/jquery-3.0.0.js"></script>
<script>
    $(function() {
        $('.mage').find('li').mouseenter(function() {
            $(this).css('opacity', 1).siblings('li').css('opacity', .4);
        });
        $('.mage').mouseleave(function() {
            $(this).find('li').css('opacity', 1);
        })
    });
</script>